The present invention relates to a light source device, in particular, a light source device in which, in the case of employing the light energy transmitted through an optical conductor cable as a photo-synthesizing light source for cultivating plants, the light energy emitted from the above-mentioned optical conductor is dispersed effectively so as to nurture plants more effectively.
In order to effectively nurture plants, a proper amount of nutritious substances, light rays, carbon-dioxide, water, the proper temperature, humidity and so on are necessary. However, it is often difficult to satisfy all of them in the right proportions. Furthermore, in order to nurture plants, a ground is needed as a home for plants. In urban districts as for instance a megalopolis, it is not readily easy to acquire a space for cultivating as for example, ground which is to be employed for cultivating plants. It is especially difficult to ensure ground that is exposed to sun so necessary for nuturing plants.
In order to solve such problems, the present applicant has previously proposed devices for focusing solar rays by means of a lense or the like and for guiding the solar rays into an optical conductor, and for further guiding them through an optical conductor to a plant cultivating device installed at an optional desired place so as to supply the necessary solar ray energy to the plants. Furthermore, the present applicant also proposed another plant cultivating device in which artificial light rays were to be added to the solar rays collected in such a manner as described above. (For instance, refer to the Japanese Patent Application No. 58-119866.) However, when light rays transmitted through an optical conductor are emitted from its edge surface, the expanding angle of the light rays' emission is narrow, for instance 45.degree., i.e. under normal conditions. Therefore, it is impossible to supply light energy over a wide area solely by emitting the light rays from an optical conductor.
By utilizing the light energy, plants perform a photosynthesis process. The nutritious substances produced by the photo-synthesis are transferred to the trunk and fruit of plants. Such transfer can be effectively performed on the condition of no light rays to be given, existence of full oxygen, or low temperature. Namely, although it is necessary to perform a photo-synthesis reaction and to cause the transfer of the nutritious substances produced by it to the plants being nurtured, the brightness and darkness periods must be alternated. In other words, the brightness period (the photo-synthesizing period) and the darkness period (the transferring period) are preferably repeated at predetermined intervals, in order for the photo-synthesis reaction to be effectively carried out.
Furthermore, in the case of nurturing plants, if the light rays are supplied to the plants intermittently (i.e. approximately several .mu.s to several ms) instead of successively, the photo-synthesizing reaction will consist of a brightness reaction and a darkness reaction and the intensive light rays will be supplied to the plants during the brightness reaction period while the light rays will not be supplied or the weak light rays will be supplied to the plants during the darkness reaction period and the growth of the plants will be promoted as a matter of course.
When the light source device is moved so as to disperse the light rays, the utilization area of the light energy will be enlarged considerably compared with the opposite case of illuminating the plants by use of a fixed light source. When employing a light source of the same capacity, the plants will be cultivated over a wider area. Furthermore, in accordance with the movement of the light source device, the position of the shadow, caused by the front leaves, changes every minutes. Therefore the brightness reaction and the darkness reaction will be repeated at timed intervals so that the growth of the plants will be promoted more effectively.
Particularly, in the case of a light source device which involves light rays emitted from the edge surface of an optical conductor, the expanding angle of the light rays' emission from the light-emitting edge of the optical conductor is narrow, as mentioned before. Therefore, it may be possible to illuminate the plants over a wider area by means of the light rays emitted from the light-emitting edge of the optical conductor by moving the light-emitting edge of the optical conductor.